Blazes are missing theire Body´s

I went to the Nether to farm some Blazerods, but the Blaze´s just where flying heads without theire rods. Even when I killed them, they dont dropped a single rod! I tried to spawn some in the Overworld, and they still missed theire rods. Maybe this got caused, because of the ftb-launcher that I tried out before that. After restarting the game, the bug was fixed.